Cutout



July 6, 1943.

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w, w W 6 9 w 5 n, 3 2 d W P 9 P 7. 7 m d `to the movable inner RessuedJuly 6, 1943 "EST AVAlLABLE COF" Allan Ramsey,

poration of Delaware Original No. 2,144,707,

Serial No. 154,973, July Evanston, Schweitzer & Conrad, Inc., Chicago,

lll., Aas slgliol' to Ill., acoriiated January 24, 1939,

22, 1937, which ls a division of Serial No. 730,075, June 9. 1934.

Application for reissu 47 Claims.

My invention relates to cutouts for electrical circuits.

This application constitutes a division of myv copendingapp1ication,fSerial No. 730,075, vfiled June 9, 1934, and assigned tothe assignee of this application, now Patent No. 2,108,993.

The fuse link assembly which I employ is of the type described andclaimed in my copending application Serial No. 671,660, filed May 18,1933, now Patent No. 2,091,453, with certain improvements to make isuniversal or adapt'it for use with the fuse device constituting a partof the plug of the cutout of the present invention, and with the dropouttype ejector cutout box of my copending application Serial No. 734,262,filed July 9,1934.

This fuse link assembly also embodies an improved visual indicatorfeature and other improvements which will hereinafter appear.

An object of my invention is to provide an improved combination of aninsulating outer sleeve having metallic ferrules constituting outerterminals, a pair of inner terminals within and adjacent one end of theouter sleeve and connected electrically with the outer terminals, one lof the inner terminals being movable toward the other end of the sleeve,with a fusible element between the inner terminals and an inner sleeveof insulating material closely surrounding the inner terminals andclosed by and attached to the movable inner terminal to move therewithtuward the other end of the outer sleeve when the fusible element fuses.

A further object of my invention is to secure the fuse tube of areplaceable fuse link to one of a pair of relatively infusible terminalsthat are interconnected by fusible means, the other terminal beingslidably mounted within the fuse tube and unattached thereto.

Still another object of my invention is to so construct the terminals`of a replaceable fuse link that they may be deformed onto the fusiblemeans interconnecting them.

A further object of my invention is to provide for deforming one end ofa terminal of a fuse link onto a fusible element and a strain element ora fusible element alone and the other end onto a flexible leadcomprising a plurality of strands of wire.

Another object of my invention is to provide a silver fusible element inthe present combination with the outer insulating sleeve and the innerinsulating sleeve closely surrounding the inner fuse terminals andclosed by and attached terminal to move therewith e May 7, 1943, SerialNo.

(Cl. 20D-117) toward the other end of me outer sleeve when the fusibleelement fuses, whereby the silver fusible element is excluded from toofree access -to atmosphere.

Further features and advantages and a. con- `crete understanding of thepresent invention will be more apparent from the following detaileddescription taken in connection with the accompanying drawing, in which:

. Figure 1 is a view villustrating my improved form of cutout mountedupon a cross arm and aiapted to receive a fuse member;

Figures 2 and 3v are parts of a longitudinal sectional view through thefuse member adapted to be mounted in the cutout shown in Figure 1(Figure 3 is to be laid below Figure 2 with the dot and dash line a--aof Figure 3 on the dot and'dash line af-d of Figure 2); and

Figure 4 is a fragmentary elevational view of the upper end of the fuselink assembly showing the same removed from the retraction spring andcable assembly and another form of terminal button applied directly tothe upper fuse terminal thereof to provide for universal application.

The cutout of my present invention comprises an outer socket member 2,which carries the main contact terminals, and the removable plug member4, which bears the fuse device for interrupting the circuit incase ofoverload or short circuit. It will be noted that -the plug member l isadapted for insertion in the top of the socket member 2, thisarrangement bearing particular relation to the type of fuse employed, aswill hereinafter appear.

The socket member 2 principally consists of a tubular member of wetprocess porcelain, or other suitable insulation, `finished with achocolate glaze inside and out, and formed externally and intermediateits ends with two longitudinal spaced annular shoulders 5-5, betweenwhich engage a split clamp 6. The clamp 6 is gripped tightly about thebody of the socket 2 by a pair of bolts 'l extending through the sidesof the clamp and engaged in suitable nuts. One end of one side of theclamp E is extended and bent laterally to form a mounting tongue 8 whichis secured, for example, to the cross-arm l0 of a transformer pole orother point of disconnection by a bracket H. The holes through the clamppart having the extending tongue 8`for the bolts I are preferably ofsquare or polygonal form, and the bolts 1 preferably have correspondingsquare or polygonal portions engaging therein -low current faults asBakelite upper end 55 the ferrule 14 BEST AVAILABLE COP" formed of casthard bronze or other suitable mato prevent turning of the bolts .indrawing up' the nuts.

The bracket II comprises four bracket parts I2, I3, Il and I5. The partI2 tits the top of the cross-arm III and has one end turned down alongone side of the cross-arm. The part I5 ilts against the opposite side ofthe cross-arm and has its lower portion offset or turned in beneath thebottom of the cross-arm. These parts I2 and I5 have outwardly directedflanges I5 at their opposite ends. The parts I3 and I4 areinterchangeable. The tongue 8 of the clamp 6 is swiveled between theextending end of the clamp part Il and the ange on the adjacent end ofthe clamp part I3 upon a carriage bolt I1 which may be loosened topermit the' cutout to be adjusted or swung to any angular position aboutthe axis of the bolt I1. and tightened to clamp the cutout rmly in theposition in which it is arranged. Carriage bolts I8 pass through theother pairs of spaced flanges I6 for gripping the bracket tightly inplace about the cross-arm III. The socket member 2 is provided withsuitable openings I9 and 2llto permit insertion of suitable lineconductors to connections to the main control terminals 'therein in amanner fully described in my copending application, of which this is adivision.

The fuse construction which I employ in my improved cutout is of thetype described and claimed in my copending application Serial No.671,660, illed May 18, 1933, and embodies a num-- ber of improvements inthis type of fuse, as will hereinafter appear. This fuse clears minor orpositively `as it clears more severe faults, as during a short circuitor heavy overload; its operation does not require explosive action, butin all cases the instantaneous collapse of the coil spring establishes adefinite and suillcient gap regardless of the amount of fault current.At the same time short circuit and heavy overload faults are cleared.without attendant danger that excessive pressure may cause destructionof the equipment. Heavy pressures occur within a small cylinder orchamber which is a part of the fuse link, and the tube proper is freelyvented. Pre-heating or corrosion does not deteriorate and result incauseless operation of the fuse element, because this element is made ofa pure metal which has proved to be vastly superior from the standpointof fits resistance to corrosion and its ability to operate at a higherpercentage of its melting point without deterioration. It is notnecessary to replace unblown fuse links after an over-current has blownother fuses in the same circuit, and a permanent and exceptionalaccuracy of fuse ratings is obtained. 'I'he time delay characteristicand short arcing time make the fuse exceptionally suitable for selectiveoperation.

Referring particularly to Figures 2 and 3, the universal fuse link showngenerally at 69 is enclosed in a tube designated 1n in its entiretywhich is preferably formed of grade X rolled or phenol condensationproduct tubing 1I rolled on a ber liner 12, or other suitable insulatingmaterial. At its upper end the outer diameter of the tube 1I is reducedat 13 to receive the upper ferrule 14 which is preferably formed ofbrass rod or other suitable material. 'At its isthreaded for mounting ina suitably threaded aperture in the plug member l, Figure 1. At outerdiameter of the tube 1I to receive the lower ferrule 16 its lower end,the is reduced at l@ which is preferably preferably chamfered terial.'Ihe extreme ends of the tube 1| are slightly, as illustrated. 'Iheupper reduced end of the tube 1I is provided with an external groove 11,and the inner surface of the ferrule 1l is provided with a downwardlyflaring or generally conical groove 18 which, when the ferrule is inplace upon the reduced upper end of the tube with its lower end in engagement with the shoulder 19, registers with the groove 11. A conicalspring snap ring 80, formed of seamless brass tubing (half hard) andsplit at 8l., engages the shoulder at the upper end of the groove 11 andthe shoulder at the lower end of the groove 18, and anchors or securesthe ferrule 1I firmly to the tube without screws or the like and atlower cost, and in a small space. At

' the same time, an exceptionally strong joint is the tube and ferrule.In asprovided between sembling these parts, the snap ring may be appliedto the groove 11 before placing the ferrule upon the tube. Then as theferrule is passed down over the upper end of the tube. the larger lowerend of the snap ring may be pressed into the groove 11 to permit passageof the ferrule into place, whereupon the ring B0 will spring out intothe conical groove l5 and, by its'engagement with the shoulder at thelower end of this groove, will anchor the ferrule firmly in place uponthe tube.

The lower reduced end 15 of the tube 1I is provided with a groove 82similar to the groove 11. and the inner surface of the ferrule 16 isprovided with anupwardly flaring or generally conical groove 83corresponding with the groove 19. A spring snap ring 8l split at 95,similar to the ring 8|),v and engaging in the grooves 82 and 83 in asimilar manner, locks or secures the'lower ferrule '16 firmly in placeupon the lower reduced end of the tube 1I. This ring 84 and the ferrule16 may be applied in the manner described in connection with 4the ring80 and the ferrule 14, and the upper end of the ferrule 16 engages theannular shoulder 8B at the upper end of the lower reduced portion 15.

The upper 'cable terminal and spring fastener which is preferably formedof brass rod or other suitable material, is flanged or headed to form abutton 9i which seats upon the upper end of the ferrule 14. The reducedportion 92,

depending integrally from the button 9|', has a material, is connectedto the lower cable terminal and spring fastener by rigidly securing itin the socketed part 91 thereof, as by inserting it in the socket andpressing or flattening the socket firmly thereon and into secureengagement therewith. The terminal and fastener 95 has a helical groovefor threaded engagement with the lower few turns of the spring 93.

The terminal 96 is knurled externally at 98 and is tapped or threadedinternally at 99 for receiving the threaded upper end of the upper fuseterminal IDII of the fuse link 69, which terminal is formed of copper orother suitable or preferred material. The lower fuse terminal IUI of thefuse link 59 is formed of similar material, and this terminal and theterminal I M are connected by a strain wire or tensile element |02arranged to bear the mechanical stress. The upper end of secured rigidlyinplace as @ser AVAILABLE Cori` and to secure the tube ||2 the wire |02is inserted in in the lower end of the a socket or opening terminal |00,and is by punching at |04 the stock of the terminal into firm bindingengagement with the wire, or by flattening the socket firmly upon thewire. The lower end of the wire |02 is inserted in a socket or openingin the terminal |0I, and is secured rigidly in place as by punching at|00 the stock of this terminal into firm binding engagement with thewire, or, as before, by flattening the socket upon the wire.

The fuse I0 preferably i's of silver, and the strain' wire |02preferably is of nickel chromium wire. The upper end of the fuse wire||0 is inserted in an opening in the terminal |00 and is secured firmlyin place therein as by punching the adjacent side of the terminal intofirm engagement therewih, or flattening the same thereon. The lower endof the wire ||0 is inserted in an opening in the terminal |0| and may besecured firmly in place therein as by punching the adjacent sides of theterminal |0| into firm engagement therewith, or flattening the samethereon. Intermediate its ends the fuse wire ||0 is coiled about thestrain wire |02.

It has been found that silver, as used in devices of this sort, hasunusual characteristics. First, there is not an appreciable absorptionof oxygen until temperatures close to the melting point arey reached,and this oxygen is released again upon a slight drop in temperature.Even if there is some oxidation, the oxide has conducting propert'essimilar to those of silver. Also, it has been found that under certaincircumstances, silver will form undesirable compounds with otherelements on blowing. In some of the experiments and tests made on fusesunder various conditions,

the blowing of the fuse appeared to be more violent than the powercurrent would seem t0 account for.

This applicant, by a combination of the silver fusible element with theand the inner insulating sleeve closely surrounding the inner fuseterminals excludes thesilver fusible element from too free access toatmosphere, and maintains this exclusion upon blowing of the fuse. Thehighly advantageous character of the silver, namely, that it appears toproduce less metallic vapor for a given rating; that it will retain itsform up to a very high temperature; that it will not oxidize and changeits rating for the oxide appears to be conductive, and that thetime-current characteristic, which is an all-lmportant factor undercertain circumstances, can readily be maintained over long periods, isutilized. Furthermore, because of the provision of the terminals |00 and|0| in relatively massive form and, therefore, relatively infusible, ascompared to the strain wire |02 and the "fuse wire |I0, the arc formedon blowing is confined substantially only to the space between theseterminals, and consequently it is possible to more readily extinguishit.

The fuse wire conductng material, preferably whose oxide is a conductor.and the comparatively high resistance strain wire |02, both arecompletely enclosed and shielded from atmosphere, gases and moisture, bya tube ||2 formed of fiber or other insulating material-` The upper endof the tube ||2 closely surrounds the upper fuse terminal |00 beneaththe integral flange ||0 thereon, and is shrunk or crimped at I5 into theannular groove IB to close the upper end of the tube ||2 against accessof atmosphere to the silver fusible element outer insulating sleeve orclear of the bottom of to the upper fuse terminal |00. The lower end ofthe tube ||2 passes `freely over and closely surrounds `the lower fuseterminal |0| and extends down to a position beneath this terminal andfrom the lower end of the fuse tube. as illustrated in Figure 3. Thetube ||2 offers no impairment to free separation of the terminals |00and |0| upon blowing of the fuse. yet,

at the same time, it is rigid throughout its length and by itsengagement at the upper end with the terminal |00 and its cooperationwith the terminal |0| holds the terminals |00 and |0| rigidly againstrelative lateral movement, such as otherwise mightresult in movement oreven crimping or twisting of the fuse wire ||0 and/or strain wire |02.

For the purpose of -providing electrical connection to the lowerterminal |0| of the fuse link 30 and setting the fuse and holding thesame set. the' low end of the terminal |0| is provided with an extension||1 formed of stranded conducting cable or other suitable material whichforms a. part of the fuse link Eiland is replaceable therewith. Severalstrands of copper cable, preferably tinned,'or depth cable are employedin the illustrated embodiment, although this may. of course, varywidely. The upper end of this cable is inserted in a socket I on thelower end of the terminal |0|, and this socket is flattened into firmengagement with the cable to secure the same therein. Within its length,the stranded cable lil is provided with a conical bushing t |20 securelyanchored in position upon the cable I il as by ilattening the upper endof the bushing into firm engagement with the cable at |2|. The lowerconical part of the bushing |20 is engageable with a clip tion. The clipand slightly hooked sides |23 of a conical socket |24 in the lower endof a tongue |25 formed integral with the lower ferrule 16 and dependingtherefrom, the integral sides |23 rounding or being hooked outwardlyfrom the base of the tongue |25 at the lower extremities of the sides|20 which round outwardly from the depressed portion |21.

The extension or stranded cable ||1 constitutes a tail extension which,when the spring 93 is retracted, extends down below the lower end of thefuse casing 'l0 and ferrule 16 so that it may be gripped convenientlyfor setting the f use and placing the spring under tension. With thespring 93 retracted, thesettingv of the fuse is accomplished by graspingthe downwardly extending tail extension and pulling the same downwardlyagainst the tension of the spring 93 until the conical bushing |20 ispositioned below the clip |22. The cable I1 above the bushing |20 isthen passed through the open side of the clip |22. Then, upon releasingthe tail extension the spring 93 draws' the bushing up firmly againstthe conical socket |24 in the clip |22, and this cooperation of thebushing |20 with the hooked sides of the clip holds the spring 93extended and the fuse in set position. A circuit is thus establishedfrom the ferrule 14, upper cable terminal and spring fastener 90,stranded conductor 95, lower cable terminal and spring fastener 96,upper fuse terminal |00, fuse wire ||0 and strain wire |02 in parallel,lower fuse terminal |0|, stranded conductor III, bushing |20, and clip|22, to the lower ferrule 16 through the tongue |25. The tail extension||1 Vbelow the conical bushing |20 may be cut off or otherwise removedafter the fuse is |22 to hold the fuse in set posi- |22 is formed by theoutstanding set, as above described, but it is to be understood thatthis removal of a part or all of the tail ex`- tension fdr setting thefuse or anchoring the lowering end of the fusey element assembly to thelower ferrule on the fuse casing is not necessary within the scope ofthe present invention.

'I'he construction shown and described herein` is a spring typeexpulsion fuse. A surrounding .sectionalized cork (not shown) and anouter enclosing tube of waterproof paper, summed Paper or the like, maybe placed around the insulating tube ||2 as in my copending applicationSerial No. 671,660, now Patent No. 2,091,453. and this tube and the fuselink i may be modified in accordance therewith. In the case of anordinary air-type expulsion fuse as disclosed in my said copendlngapplication, Serial No. 671,660, now Patent No. 2,091,453, or in thecase of the drop out type ejector cutout box of my copending applicationSerial No. 734,262, filed July 9, 1934, the spring and cable assembly92, 05 and the assoelated terminals 00 and 90 may'be removed byunscrewing the upper fuse terminal |00 of the fuse link 6l from thetapped or threaded socket in the lower end of the terminal 98. Then, bymerely threading the upper end of the upper fuse terminal |00 into abutton |35 of suitable conducting material and flanged radially as shownin Figure 4, the same fuse link 68 is adapted for use with the ordinaryair type expulsion fuse or with the drop out type ejector cutout box ofmy copending application. Serial No. 734,262. 'Ihis makes the fuse link60 universal, in that it is adapted for use in different types of fusehousings or mountings.

The cylinder or tube I I2, which encloses the fuse element |I0 andstrain wire |02 of the fuse link 69, in addition to confiningthe arc ina very small space and preventing charring and metal spattering onthetube liner 12, and with its upper end closed to prevent too free accessof atmosphere to the fusible link and maintain the closure upon fusingof the link, serves, by its downward extension below the ferrule 'I6 toperform the additional function of giving a visual indication when thefuse has been blown. Since the upper end of the tube or cylinder ||2 issecured to the upper fuse terminal |00 by crimping or shrinking, intothe groove IIE, it will be apparent that thisnfitube |I2 will moveupwardly with the upper fuse' terminal |00 and lower cable terminal andspring fastener lli upon retraction of the spring 93. Consequently, theabsence oi the projection of the lower end of the tube |I2 down from thebottom |40 of the ferrule I6 gives a visual indication that the fuse hasblown and the spring 03 retracted. However, the presence of the lowerend of the tube I I2 beneath the bottom |40 of the ferrule I6indicatesvisually that the fuse has not blown and that the device is inoperative relation. The lower end of the tube |I2, the absence orpresence of which gives this indication, is indicated at |42 in Figure3.

The current of my invention is set in operative relation by assemblingthe fuse parts as shown in Figures 2 and 3, and then screwing the upperthreaded end 65 of the upper ferrule T4 into the plug member 4. The plug4 is then inserted into the socket 2, as illustrated in Figure 1.

The upper ferrule 'I4 is provided with an annular groove |50 havingspaced vent openings |52 therein that are normally closed by a pressureband |54 which is held in place by a coiled lock spring |50. On blowingof the fuse link B9, suilicient pressure is generated within vthe tubely over the other fuse BEST AVAILABLE com l 1l 0 lift the bnd l.

96, whereupon a new fuse link 00 is applied by.

screwing the upper terminal thereof into the tapped opening in theterminal l0. The fuse link B0 and spring and cable assembly are theninserted into the fuse tube Il through the upper end of the upperferrule '|4. The tail extension II'I is then grasped and drawndownwardly against the tension of the spring50 and the conical bushing|20 engaged in the clip |22, whereupon the excess tail extension belowthe bushing |20 may be cut oir with a pair of pliers.

While I have shown and described my invention with reference to theparticular details of construction of one embodiment, it is to beunderstood that the invention may appear ln dltferent forms and andvariations such as will suggest themselves to one skilled in the art,andv it is to be 'further understood that I consider all suchmodifications and variations to be included within the scope of myinvention.

I claim:

1. In a device of the class described, a movable system including amovable terminal member, a coil spring normally under tension andconnected to said terminal member, a fuse link having a fuse terminalfor connection with the terminal of said movable system, and a secondfuse terminal, a rigid tubular insulating envelope secured to the fuseterminal for connection with the terminal of the movable system and,being movable therewith and fitting telescopicalr terminal, and afusible element within said envelope, said tubular envelope being out ofcontact with the fusible element.

2. In combination, an outer sleeve, a pair of fuse terminals within saidsleeve, a fusible link between said terminals, an inner sleeve closelysurrounding said inner terminals and said fusible link and projectingfrom said outer sleeve, means to retract the inner sleeve when the linkis fused.

3. In a device of the class described. a fuse tube, a movable systemwithin said tube including a movable terminal member, a coil springnormally under tension and connected to said terminal member, a fuselink having a fuse terminal for connection with the terminal-of saidmovable system and a. second fuse terminal, a rigid insulating envelopesecured to the fuse terminai for connection with the terminal of themovablesystem, said envelope fitting telescopically over the other fuseterminal and extending from the end of the fuse 'tube for indicating thecondition of the fuse, and a-fusible element within said envelope. Y

4. In combination, a fuse tube, a movable system within said tubeincluding a movable terminal and a coil spring normally under tension isthen removed from the plug 4 with numerous modifications and tached tothe movable inner AVAILABLE COP and connected to said terminal, a fuselink assembly for connection to said terminal. and means lor connectionto the movable system and projecting from the end ofthe fuse tube whenthe spring is under tension and retracted from the end of the fuse tubeupon retraction of the spring to indicate the condition of the fuse.

5. In a fuse, an insulating outer sleeve having metallic ferrulesconstituting outer terminals, a pair of inner terminals within andadjacent one end of the outer sleeve and connected electrically with theouter terminals, one of said inner terminals being movable toward theother end of the sleeve, a fusible element between the inner terminals,and an inner sleeve of insulating material closely surrounding the innerterminals land the fusible element and closed by and atterminal adaptedto move therewith toward the other end of the outer sleeve when thefusible element fuses.

6. In a fuse, an insulating outer sleeve having metallic ferrulesconstituting outer terminals, a pair of inner terminals within andadjacent one end of the outer sleeve and connected electrically with theouter terminals, one of said inner terminals being movable toward theother endof the sleeve, a fusible element between the inner terminals.and an inner sleeve of insulating material closely surrounding the innerterminals and the fusible element and closed by and attached to themovable inner terminal adapted to move therewith toward the other end ofthe outer sleeve when the fusible element fuses, the other innerterminal being adapted for relative movement through the inner sleeveand out of the end thereof.

7. In a fuse, an insulating outer sleeve having metallic ferrulesconstituting outer terminals, a pair of inner terminals within andadjacent one end of the outer sleeve and connected electrically with theouter terminals, one of said inner terminals being movable toward theother end of the sleeve` a fusible element between the inner terminals,an inner sleeve of insulating material closely surrounding the innerterminals and the fusibleelement and closed by and attached to themovable inner terminal, and a spring for retracting the movable terminaland the inner sleeve toward the other end of the outer sleeve when thefusible element fuses.

8. In a fuse, an insulating outer sleeve having metallic ferrulesconstituting outer terminals, a pair of inner terminals within andadjacent one end of the outer sleeve and connected electrically with theouter terminals, one of said inner terminals being movable toward theother end of the sleeve, a silver fuse link between the inner terminals,and an inner sleeve of insulating material closely surrounding the innerterminals and the fusible element and closed by and attached to themovable inner terminal adapted to move therewith toward the other end ofthe outer sleeve when the fusible element fuses.

9. In a fuse, an outer insulating member having a bore of relativelylarge diameter, an inner insulating member small diameter. terminals anda fusible element closely surrounded by the bore of the inner member,one terminal forming a permanent closure for one end of the bore of theinner insulating member, and means for moving said latter terminal andthe inner insulating member when the fusible element fuses to lengthenthe arc within the inner bore.

10. In a. fuse, an outer insulating *member havhaving a bore ofrelatively ing a bore of relatively 'large diameter, an inner insulatingmember having a bore of relatively small diameter, terminals and afusible element closely surrounded by the bore of the inner member, oneterminal forming a permanent closure for one end of the bore of theinner insulating member, and means for moving said latter terminal andthe inner insulating member when the fusible element fuses to lengthenthe arc first within the bore of the inner insulating member and laterwithin the bore of the outer insulating member.

11. In a fuse, an outer insulating member having a bore of relativelylarge diameter, an inner insulating member having a bore of relativelysmall diameter, terminals and a fusible element closely surrounded bythe bore of the inner member, one terminal forming a permanent closurefor one end of the bore of the inner insulating member, and means formoving said latter terminal and the inner insulating member when thefusible element fuses to lengthen the arc rst within the bore of theinner insulating member and later within the bore of the outerinsulating member, one terminal and the adjacent end of the arc beingclosely surrounded by the relatively small diameter bore of the innerinsulating member throughout the duration of the arc.

12. In a fuse, an outer insulating member having a bore of relativelylarge diameter, an inner insulating member having a bore of relativelysmall diameter, terminals and a silver fuse link closely surrounded bythe bore `of the inner member, one terminal forming a permanent closurefor one end of the bore of the inner insulating member, and means formoving said latter terminal and the inner insulating member when thefusible element fuses to lengthen the arc within'the inner bore.

13. An article of manufacture comprising a renewable unit for a fusecomprising a pair of fuse terminals, a stress sustaining link connectingsaid terminals, a fusible endsto said terminals and having itsintermediate portion formed into a coil and independent of saidsustaining link, and an insulating sleeve closely surrounding the fuseterminals but being out of contact with the fusible link and the stresssustaining link and lbeing closed by and attached to one of said innerterminals.

14. A renewable unit for a fuse comprising a pair of fuse terminals,stress sustaining and fusible links connecting said terminals, aninsulating sleeve closely surrounding the fuse terminals and the stresssustaining and fusible links and closed by and attached to one of saidterminals` and means interchangeably attachable to said latter terminalfor adapting the unit for use in an ordinary air expulsion fuse and in aretraction fuse having means for moving one of said terminals.

15. In combination, an outer sleeve, a pair of fuse terminals withinsaidV sleeve, a fusible link between said terminals. and an inner sleeveclosely surrounding said inner terminals and said fusible link andprojecting from said outer sleeve,

said inner sleeve being adapted to be `drawn into terminals and thefusible by and attached to one of link connected at its menirforaccumulation of pressure upon blowing of the fuse, one fuse terminalbeing movablev within the inner sleeve for elongation of the arc withinsaid sleeve and movable from the inner sleeve to release the pressureand vpermit an outward flow ofv gases from the sleeve, said inner sleeveand the other'terminal being movable further to elongate the arc.

18. A renewable fuse link'comprising a first terminal having a threadedstud at one end, an arcing tip at the other end, and having anintermediate groove, a second terminal comprising an arcing tip at oneend and a flexible lead attached to the other end, a fusible element,said arcing tips having means for mechanically gripping the ends of saidelement and a fiber tube surrounding said terminals and the element andimum diameter of the being anchored at one end'to said groove, saidflexible lead extending the tube. A

19. 'I'he combination with claim i8 of a stress out of the open end ofsustaining link connected between the arcing tips x to relieve thefusible element of tension, said tube being out of contact with theelement and the stress sustaining link, said second terminal fittingloosely in the bore of the tube, whereby it tends 'to be expelled uponthe generation of gases by the arc.

20. In a fusible current interrupter, a link comprising the combinationof a current sensitive element adapted to be fused upon the passagetherethrough of current in excess of a predetermined value for apredetermined period of time, a relatively thin walled tubular envelopeof substantially uniform bore surrounding the said element but being outof contact therewith, rigid metal terminals for the element, saidterminals being of a, current carrying capacity high enough to remainunfused upon the passage therethrough of any value of V current withinthe capacity for which the interrupter is designed, said tubularenvelope extending beyond the ends of the element and telescoping withsaid terminals, one end of said tube being closed by the correspondingone terminal and the other terminal substantially filling and beingslidable in the bore of the tubular envelope, said latter terminal beingadapted to be moved envelope upon fusing of said element.

21. The link of claim 20 further characterized by a coupling headforming a rigid extension of the said one terminal for supporting oneend of the link, and a flexible lead joined to and extending from saidother terminal.

22. A terminal for a fuse link comprising a rodarc between the fusiblevelement and the flexible lead.

the same mechanically and electrically,`

`of the socket upon the g relatively closely 23. The combination ofclaim 22 wherein the collapsed sockets are of a maximum transverse notin excess of the maxdimension substantially rodlike section.

24. The terminal of claim 22 wherein the second socket has localizedindentations of the walls element to produce localized deformations ofthe element and the socket to improve the mechanical and electricalconnection of the same.

25. A terminal for a fuse link comprising a central rodlike sectionhaving sockets upon each end, a flexible lead disposed in one socket,the walls of the socket being deformed to make connection mechanicallyand Aelectrically between the terminal and the lead, a fusible elementand a strain element disposed in the second socket, said second sockethaving the walls thereof collapsed upon the fusible element and thestrain element, the walls of the second socket being locally deformed toproduce localized deformation of the socket and chanical and electricalconnection of the ments with said 'secondsocket.

26. The method of joining a rodlike terminal to a fusible element whichcomprises forming a socket in one end of the rodlike terminalof aninternal diameter substantially in excess of the diameter of the fusibleelement, introducing the fusible element into the socket, collapsing thewalls of said socket into contact with the sides of the fusible element,and applying localized pressure to a wall of the socket adjacent thefusible element. whereby a localized deformation of the socket and theelement is produced to improve the mechanical and electrical bondbetween the terminal and the element.

27. A fuse link comprising an outer cylindrical terminal member and aninner cylindrical terminal member, said members having sockets facingtowards each fuse wire embraced within and held by said sockets, a smallbore thin-walled fiber tube anchored to and closed by the outer terminaland embracing the inner terminal but permitting free expulsion of theinner terminal from the adjacent end of the tube, said inner terminalconstituting a piston-like obstruction to the escape of gases generatedby the arc produced upon melting of the fusible element, and a flexiblelead secured to the inner terminal member and extending out of the openend of the tube.

28. In a fuse link, a-terminal having a knurled portion, and a sleeve ofinsulation frictionally engaging said knurled portion, said knurlingextending longitudinally of said terminal and sleeve to prevent relativerotation thereof.

29. In a fuse link, a terminal having a peripheral groove and a knurledportion, and a sleeve of insulation frictionally engaging said knurledportion, said knurling extending longitudinally of said terminal andsleeve to prevent relative rotation thereof and said sleeve interiittingwith said groove to prevent relative ment between it and said terminal.

30. In `a fuse link, a terminal having an attaching portion at one end,a fuse element receiving portion at the other end and a'peripheralgroove and a knurled portion intermediate said ends, and a fiber tubefrictionally engaging said knurled portion and shrunk into said groovefor preventing relative rotary and axial movement between said terminaland said sleeve.

31. In a fuse, in combination, an insulating the element to improve themel other, a strain wire and a silverv longitudinal movenais andattached to one of them,

outer sleeve, a pair of relatively infusible terminais within saidinsulating outer sleeve, a fuse wire interconnecting said relativelyinfusible terminals, and an inner sleeve of insulating maierialsurrounding said relatively nfusible termisaid inner sleeve ofinsulating material being appreciably longer than the distance betweensaid relatively` infusible terminals and relatively short with re`\,lspect to said insulating outer sleeve.

32. A renewable fuse link comprising, in ccmbination; a first terminalhaving #support means at one end, an arcing 'tipi at |the other end. anda groove intermediate said ends; a second terminai comprising an arcingtip at one end and a flexible lead attached to the other end, a fusibleelement, said ar-cing tips having means for mechanically gripping theends of said fusible element, and an insulating tube surrounding saidfirst and second terminals and said fusible el'ement and being anchoredat one end in said groove, said flexible lead extending out of the otherend of said insulating tube.

33. In a fuse link having a fusible element, a terminal for said fusibleelement having a cur` rent carrying capacity such that it remainssubstantially unfused uponl flew of anyvalue of current withinthe'intended interrupting capacity of said fusible element, one end ofsaid terminal being formed to receiveone end of said fusible element andbeing collapsed and locally deformed thereon to provide mechanical andelectrical cen nections thereto, and means at the other said terminalfor connecting it-'in an electric circuit. l

34. A fuse link comprising, in combination; a iirst terminal having anattaching portion at one end, a fusible element receiving portion at theother end, Iand a peripheral groove and a knurled portion intermediateits ends; a tubular insulating member at one end frictionally engagingsaid knurled portion and interiitting with said groove; a secondterminal movably mounted in said tubular insulating member and having afusible element receiving portion at one end and a con'- ductorreceiving portion at the other end; and a fusible elementinterconnecting said fusible element receiving portions.

35. A fuse link comprising. in combination; a

end, a fusible element receiving portion at, the other end, and aperipheral groove and a knurled portion intermediate its ends; a tubularinsulating member at one end frictionally engaging said knurled portionand interfitting with said groove: a second terminal movably mountedentirely within said tubular insulating member and having a fusibleelement receiving portion at one end lar member of insulating material,a fusible section in said tubular member, a. flexible terminal connectedto one end of said fusible section and extending out of one end of saidtubular member, a rigid terminal connected to the other end of saidfusible section and extending out of the other end of said tubularmember, a fixed head on the end of` -first terminal having an attachingportion at one said fuse tube, fusible means EST AVAlLABLE COF"` 7 outerend of said rigid terminal, and a removable head surrounding said fixedhead.

37. A renewable fuse link for mounting in different types oi fusehousings comprising, a fuse |tube, a terminal at one end of said fuseltube, a flexible lead extending out of the other end of interconnectingsaid terminal and said flexible lead, and means interchangeablycooperating with said terminal for adapting said fuse link for use insaid different types of fuse housings.

38. A renewable fuse link for mounting in different types of fusehousings comprising, a fuse tube, a terminal at one end of said fusetube, a flexible lead extending out of the other end of said fuse tube,fusible means interconnecting said terminal and said flexible lead.and'means interchangeably attachable to said terminal for adapting saidfuse link for use in an ordinary air expulsion fuse housing and in aretraction fuse housing having means for moving said terminal.y

39. A renewable fuse link for mounting in different types of fusehousings comprising, a fuse tube, a vterminal at one end of said fusetube, a flexiblel lead extending out of the other end of said fuse tube,fusible means interconnecting said terminal and said flexible lead.threaded means on said terminal, and an adapter threaded for engagementwith said threaded means and having a flanged head for adapting saidfuse link for use in different types of fuse housings.

40. A renewable fuse link for mounting in diffrrent types offuse'housings comprising. a. fuse tube. a relatively infusible terminalattached to one end of said fuse tube, a flexible lead extending out ofthe other end of said fuse tube, fusible means interconnecting 'saidterminal and said flexible lead, a threaded stud on said terminal, andan adapter threaded at one end for attachment to said threaded stud andhaving a flanged head at the other end for adapting said fuse link foruse in an ordinary air expulsion fuse housing and in a' retraction fusehousing having means for moving said terminal.

41. A unitary fuse link structure adapted to be positioned in a fusecartridge, said link structure comprising a tubular element, aconducting element carried by the upper end of said tubular element forengagement with a terminalcon ducting means extending from the other endof said tubular element and of sufficient length to extend out of thefuse cartridge for connection to a second terminal, a fusible elementelectrically connecting said conducting means and said first mentionedconducting element, and resilient means tensioning said fusible elementand acting to quickly increase the gap between the parts of the fusibleelement when the latter is ruptured by overload current, said conductingmeans being unattached to the tubular element and movable relative tothe lower end thereof by the action of the resilient means after ruptureof the fusible element.

42. A unitary fuse link structure adapted to be positioned in 'a fuse,cartridge, said link structure comprising a tubular element, aconducting element carried by the upper end of said tubular element forengagement with a terminal, conducting means extending from the otherend of said tubular element and of sufficient length to extend out ofthe fuse cartridge for connection to a second terminal, a fusibleelement electrically connecting said conducting means and said firstmentioned conducting element, and coil spring means disposed within thefuse cartridge and externally of said the fusible element when thelatter is rupturedv by overload current, said conducting means beingunattached to the tubular element and movable relative to the lower endthereof by the action of said coil spring means after rupture'oi thefusible element.

43. In a fuse, an insulating outer sleeve having outer terminalsadjacent its ends, a pair of inner terminals within said sleeve, one ofsaid inner terminals being connected to one of said outer terminals andthe other inner terminal including a flexible lead for connection` tothe other outer terminal, a fusible element interconnecting said innerterminals, material mounted on said one inner terminal and extendingover said i'usible element and said an innersleeve of insulatingv BESTAVAM .AaLECOP4 tubular element and acting other inner terminal, saidvinner sleeve being appreciably longer relatively short with respect tosaid outer sleeve.

' and spring means within said outer sleeve tensioning said fusibleelement and acting to quickly increase the .gap between the parts of thefusible element when the latter is ruptured by overload current.

44. In a fuse, an insulating outer sleeve having outer terminalsadjacent its ends, apair of inner terminals within said sleeve, one ofsaid inner terminals being connected to one of said outer terminals andthe other inner terminal including a exible lead for connection to theother outer terminal, a fusible element interconnecting said innerterminals, an inner sleeve of insulating material mounted on said oneinner terminal and extending over said fusible element and said otherinner terminal, said inner sleeve thansaid fusible element andvMbination, a fuse tube,

being appreciably longer: than said fusible element and relatively shortwith respect to said outer sleeveand coil spring means disposed withinsaid outer sleeve and externally of said inner sleeve and acting totween the parts of the fusible element when the latter is ruptured byoverload current.

45. A replaceable fuse link comprising, a pair of relatively infusibleterminals, fusible means interconnecting said terminals, and a sleeve ofinsulating material surrounding said terminals and said fusible meansand being appreciably longer than the distance between said terminals.

46. A replaceable fuse link comprising, in combination, a pair ofrelatively infusible terminals, fusible means interconnecting saidterminals, a

vsleeve of insulating material surrounding said terminals and saidfusible means and being appreciably longer than the distance betweensaid terminals, one of said terminals being locatedl at one end'oi' saidsleeve and the other being freely movable out of its other end, andconducting means connected to said other terminal an'd extending out ofsaid other end of said sleeve.

47. A replaceable fuse link comprising. in coma relatively infusibleterminal at one end of said fuse'tube, a conductor extending out of theother end oi' said fuse tube including a relatively infusible terminaland a flexible lead, and strain rand Vfusible elements interconnectingsaid terminals, said fuse tube being appreciably longer than thedistance between said terminals and said conductor being freely movableout of said fuse tube on blowing of said strain and fusible elements.

quickly increase the gap be-`

